Improvement in pulley-blocks



STATES .PATENT OFFICE?.

. AFERDINAND C.' D. MCKAY, ELMIRA, NEW YORK."v

IMPROVEMENT IN .PULLEY-BLOCKS.

Specification forming part of Letters Patent No. 149,941, dated April21, 1874; application filed September 30, 1873.

CASE B.

To all whom it 'may concern: l

Beit known that I, FERDINAND G. D. Mc- KAY, of Elmira, New York, haveinvented an Improvement in Pulley-Blocks for Operating Doors, and forother purposes, of which the following is a specification:

This invention relates to certain 'improvements in pulley-blocksspecially designed for closing doors, and for holding them more or lessopen,when desired, `although it is evident that it may be employed invarious positions and for many purposes. The invention consists of apulley having a slot or opening mounted on its axis in such a mannerthat thev distance from its circumference, with respect to said axis,may be changed, in order to procure a grr ater or less eccentricarrangement of said pulley, as will be hereinafter described.

In the drawing, Figure l is a view, partly in section, of my pulleyapplied to a casing for operating a door or other object. Fig. 2 is aside view of the same; and Fig. 3, a modication thereof.

The letter A lrepresents a pulley having, preferably, a slot or opening,a, cut diametric ally through it, and in this slot is arranged` the rodor bolt B, which forms the axis or fulcrum of the pulley. The pulley Ais, by preference, secured in position on the axis by a nut, b, theobject of such being that 'the' distance from the circumference of thepulley, with respect to its axis or fulcrum, may be changed, in order toincrease or diminish its eccentric arrangement.

The principal feature of this arrangement is that a spring or weightmuch lighter than the object to be balanced may be employed, the degreeof the eccentric arrangement of the pulleydepending upon thev weight ofthe object to be balanced, as the heavier the object and the lighter thecounter-balance the greater must be the degree of eccentricity.

In order to adapt the pulley as a device for closing doors, or forholding them open at any desired position, I secure one end of a coiledspring, C, to the axis B, and attach its other end to an outer casing,D, which latter may bedivided into two parts by a division-plate, c, thespring being arranged on one side of the Iby the door.

, division-plate and the pulley on the other.

One side of said casing is provided with ears or anges d d, in which arejournaled two small rollers,E E, for the purpose of adapting the deviceto doors opening right or left. One end of a cord or chain, F, isattached to the pulley A, and is passed around the same several times,and its free end is connected to one end of an arm, G, attached to thedoor or wall, as the case may be. The rear side of the case D isprovided, in the present instance, with a screw-threaded shank, H, forattaching the device to the door, 0r to the wall, by the employment. ofwhich I am not required to use special tools to apply the same;4 but Ido not design to apply the device in this manner at all times, as themeans ofr doing so are various. hollow, Aand place the spring O withinit, and support the axial bearing of the pulley in a bracket, I, havinga screw-threaded shank, as shown.

Instead of employing a spring to counterbalance the object, I design touse a cord or chain and a weight or weights, and accom plish by thismeans the result obtained by the use of a spring.4

By means of the pulley capable of ybeing changed ou its axis, andarranged eccentrically, there is one dead-point occurring at eachrevolution of the same; and hence, when the door is opened, and thepulley comes to this point in respect to the door, the latter will reAmain in a xed or stationary position, due to the fact that there is notsufficient force in the counter -balance, be it a weight or spring, toovercome the resistance exerted on the pulley If an oval-shaped pulleyis ein ployed, there will be two dead-points, each occurring when thepulleyis in a horizontal plane and in a many-sided pulley the number ofdeadpoints will be correspondingly increased. Instead of the pulleybeing formed with a diametrical slot, so as to be'mounted on its axis,various other formed slots or openings may be resorted to to accomplishthe result desired, viz: To sov connect the pulley with its ,axis thatthe location of its axial bearing may be changed, with respectto itscircumference, to

In some instances I make the pulley A.

secure e greater or less eccentric arrangement for the object eserbed.

It is evident that the pulley and counter balance may be used inelevators, dumb-waiters .ehende1iers, Ste.

A pul1ey-b10ck constructed with an elongated slot, and adjustablyconnected with its exis, so that the dista-nce from its circumference toits exis or fulerum een be changed to regulate its eecentrieity, saidpulley adapted to operate in connection with a spring or Weight and Cordor chain7 substantially as described.

In testimony that I claim the foregoing I have hereunto set my handthis13th day of September, 1873.

F. e. D. MQKAY.

